Affiliation:
1. Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences Chinese Academy of Sciences Shanghai 201602 China
2. University of the Chinese Academy of Sciences Beijing 100049 China
3. Department of Biology, Centre for Novel Agricultural Products (CNAP) University of York York YO10 5DD UK
Abstract
Summary
Bacterial pathogens inject effector proteins inside plant cells to manipulate cellular functions and achieve a successful infection. The soil‐borne pathogen Ralstonia solanacearum (Smith), the causal agent of bacterial wilt disease, secretes > 70 different effectors inside plant cells, although only a handful of them have been thoroughly characterized. One of these effectors, named RipI, is required for full R. solanacearum pathogenicity. RipI associates with plant glutamate decarboxylases (GADs) to promote the accumulation of gamma‐aminobutyric acid (GABA), which serves as bacterial nutrient.
In this work, we found that RipI can also suppress plant immune responses to bacterial elicitors, which seems to be unrelated to the ability of RipI to induce GABA accumulation and plant cell death.
A detailed characterization of the RipI features that contribute to its virulence activities identified two residues at the C‐terminal domain that mediate RipI interaction with plant GADs and the subsequent promotion of GABA accumulation. These residues are also required for the appropriate homeostasis of RipI in plant cells and the induction of cell death, although they are partially dispensable for the suppression of plant immune responses.
Altogether, we decipher and uncouple the virulence activities of an important bacterial effector at the biochemical level.
Funder
Chinese Academy of Sciences